Water is well known for its fire extinguishing properties and remains the predominate material used to extinguish or prevent certain types of fires. Water has a high heat capacity and high heat of vaporization such that when water is sprayed onto a fire the water that reaches the flames absorbs the heat of the fire and cools the article to below its combustion temperature. Water also deprives the fire of oxygen. Often the heat of the fire turns a portion of water into vapor before it can reach the flames. Since water vapor is heavier than air it displaces the oxygen surrounding the fire thereby suffocating the fire. When water is dropped from an airplane a portion of the water can evaporated before reaching the fire. Water mixed with fire retardants can enhance the fire extinguishing aspects of the water.
Aircraft have become incredible fire fighting tools when the fire is located in a forest or other remote area. While a plane can hold an incredible about of water, it must land and refill the water tanks before each use. For this reason planes capable of drawing water from a lake have certain advantages. Planes such as the Bombardier 415 are capable of drawing water from a lake for use in dispensing over forest fires. The AT802 Fire Boss holds 400 to 500 gallons of water and is capable of being filled within 12 seconds while the aircraft is skimming over the surface of the water. An advantage to amphibious aircraft is that they can be refilled quickly but are not set up to include fire retardant. A significant disadvantage often encountered using untreated water to extinguish a fire is that much of the water ends up being wasted. Untreated water can evaporate before it can reach the base of the fire, where the combustible fuel for the fire resides. Further upwards of 90% of the water that does manage to reach the flames simply runs off into the ground without remaining on the trees, foliage or structure that is burning. Moreover, considerable effort must be made to continuously soak objects with water near the fire that could ignite. The evaporated and runoff water must be constantly replaced.
Ammonium phosphate fertilizer added to water is another method of firefighting used to slow and cool down a fire. Lockheed P2V's can carry 2,400 gallons of fire fighting fluid. McDonnell Douglas DC-10 may hold up to 12,000 gallons of fire fighting fluid in an exterior belly mounted tank. While this is an effective fire retardant, Forest Service officials were sued to prevent the fire retardant from being dropped near streams and lakes except when human safety is at risk. The substance consists primarily of ammonium phosphate, which has been known to kill off fish. In 2009, when ammonia in retardant dropped on wildfires near Santa Barbara, Calif., the retardant killed protected steelhead trout in the Santa Ynez River. In 2002, a slurry bomber dumped between 1,000 and 2,000 gallons of fire retardant containing sodium ferrocyanide on the Fall River south of Bend, Oreg., which immediately killed all of the river's fish, an estimated 21,000 juvenile brown trout, redband trout and mountain whitefish over a six-mile stretch. Fire retardant manufacturers have cut the ammonium in retardant over the last decade which now affects whether the material is effective.
The purpose of the fire retardant is to give firefighters time to mount a ground attack. Fire retardant is formulated to slow down the combustion of trees, brush, and grass. The ground forces clear away flammable material in a wide line around the edges of the fire. They hem in the flames and eventually a soaking rain falls or the fire just burns itself out.
What is lacking in the art is a device that will increase the effectiveness of water that is picked up by planes without landing by integrating an apparatus for introducing a media, such a as a super absorbent polymer, into amphibious aircraft.